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8339161: ZGC: Remove unused remembered sets

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Reviewed-by: aboldtch, stefank
This commit is contained in:
Joel Sikström 2024-09-23 12:28:43 +00:00 committed by Stefan Karlsson
parent 384deda65f
commit 37ec80df8d
7 changed files with 29 additions and 95 deletions
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13
src/hotspot/share/gc/z/zHeap.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2015, 2023, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2015, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -248,8 +248,7 @@ void ZHeap::free_page(ZPage* page) {
_page_table.remove(page);
if (page->is_old()) {
page->verify_remset_cleared_current();
page->verify_remset_cleared_previous();
page->remset_delete();
}
// Free page
@ -261,12 +260,10 @@ size_t ZHeap::free_empty_pages(const ZArray<ZPage*>* pages) {
// Remove page table entries
ZArrayIterator<ZPage*> iter(pages);
for (ZPage* page; iter.next(&page);) {
if (page->is_old()) {
// The remset of pages should be clean when installed into the page
// cache.
page->remset_clear();
}
_page_table.remove(page);
if (page->is_old()) {
page->remset_delete();
}
freed += page->size();
}

26
src/hotspot/share/gc/z/zPage.cpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2015, 2023, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2015, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -78,27 +78,16 @@ void ZPage::reset_seqnum() {
Atomic::store(&_seqnum_other, ZGeneration::generation(_generation_id == ZGenerationId::young ? ZGenerationId::old : ZGenerationId::young)->seqnum());
}
void ZPage::remset_initialize() {
// Remsets should only be initialized once and only for old pages.
void ZPage::remset_alloc() {
// Remsets should only be allocated/initialized once and only for old pages.
assert(!_remembered_set.is_initialized(), "Should not be initialized");
assert(is_old(), "Only old pages need a remset");
_remembered_set.initialize(size());
}
void ZPage::remset_initialize_or_verify_cleared() {
assert(is_old(), "Only old pages need a remset");
if (_remembered_set.is_initialized()) {
verify_remset_cleared_current();
verify_remset_cleared_previous();
} else {
remset_initialize();
}
}
void ZPage::remset_clear() {
_remembered_set.clear_all();
void ZPage::remset_delete() {
_remembered_set.delete_all();
}
void ZPage::reset(ZPageAge age) {
@ -123,7 +112,6 @@ void ZPage::reset_top_for_allocation() {
void ZPage::reset_type_and_size(ZPageType type) {
_type = type;
_livemap.resize(object_max_count());
_remembered_set.resize(size());
}
ZPage* ZPage::retype(ZPageType type) {
@ -216,10 +204,6 @@ void ZPage::verify_remset_cleared_previous() const {
}
}
void ZPage::clear_remset_current() {
_remembered_set.clear_current();
}
void ZPage::clear_remset_previous() {
_remembered_set.clear_previous();
}

8
src/hotspot/share/gc/z/zPage.hpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2015, 2023, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2015, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -155,9 +155,8 @@ public:
void clear_remset_range_non_par_current(uintptr_t l_offset, size_t size);
void swap_remset_bitmaps();
void remset_initialize();
void remset_initialize_or_verify_cleared();
void remset_clear();
void remset_alloc();
void remset_delete();
ZBitMap::ReverseIterator remset_reverse_iterator_previous();
BitMap::Iterator remset_iterator_limited_current(uintptr_t l_offset, size_t size);
@ -182,7 +181,6 @@ public:
void verify_remset_cleared_current() const;
void verify_remset_cleared_previous() const;
void clear_remset_current();
void clear_remset_previous();
void* remset_current();

4
src/hotspot/share/gc/z/zPageAllocator.cpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2015, 2023, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2015, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -733,7 +733,7 @@ retry:
page->reset_top_for_allocation();
page->reset_livemap();
if (age == ZPageAge::old) {
page->remset_initialize_or_verify_cleared();
page->remset_alloc();
}
// Update allocation statistics. Exclude gc relocations to avoid

39
src/hotspot/share/gc/z/zRelocate.cpp
View File

@ -848,7 +848,7 @@ private:
to_page->reset(to_age);
to_page->reset_top_for_allocation();
if (promotion) {
to_page->remset_initialize();
to_page->remset_alloc();
}
// Verify that the inactive remset is clear when resetting the page for
@ -943,35 +943,15 @@ public:
return ZGeneration::old()->active_remset_is_current();
}
void clear_remset_before_reuse(ZPage* page, bool in_place) {
void clear_remset_before_in_place_reuse(ZPage* page) {
if (_forwarding->from_age() != ZPageAge::old) {
// No remset bits
return;
}
if (in_place) {
// Clear 'previous' remset bits. For in-place relocated pages, the previous
// remset bits are always used, even when active_remset_is_current().
page->clear_remset_previous();
return;
}
// Normal relocate
// Clear active remset bits
if (active_remset_is_current()) {
page->clear_remset_current();
} else {
page->clear_remset_previous();
}
// Verify that inactive remset bits are all cleared
if (active_remset_is_current()) {
page->verify_remset_cleared_previous();
} else {
page->verify_remset_cleared_current();
}
// Clear 'previous' remset bits. For in-place relocated pages, the previous
// remset bits are always used, even when active_remset_is_current().
page->clear_remset_previous();
}
void finish_in_place_relocation() {
@ -1017,7 +997,7 @@ public:
ZPage* const page = _forwarding->detach_page();
// Ensure that previous remset bits are cleared
clear_remset_before_reuse(page, true /* in_place */);
clear_remset_before_in_place_reuse(page);
page->log_msg(" (relocate page done in-place)");
@ -1029,11 +1009,6 @@ public:
// Wait for all other threads to call release_page
ZPage* const page = _forwarding->detach_page();
// Ensure that all remset bits are cleared
// Note: cleared after detach_page, when we know that
// the young generation isn't scanning the remset.
clear_remset_before_reuse(page, false /* in_place */);
page->log_msg(" (relocate page done normal)");
// Free page
@ -1292,7 +1267,7 @@ public:
new_page->reset(to_age);
new_page->reset_livemap();
if (promotion) {
new_page->remset_initialize();
new_page->remset_alloc();
}
if (promotion) {

27
src/hotspot/share/gc/z/zRememberedSet.cpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -55,18 +55,10 @@ void ZRememberedSet::initialize(size_t page_size) {
_bitmap[1].initialize(size_in_bits, true /* clear */);
}
void ZRememberedSet::resize(size_t page_size) {
// The bitmaps only need to be resized if remset has been
// initialized, and hence the bitmaps have been initialized.
if (is_initialized()) {
const BitMap::idx_t size_in_bits = to_bit_size(page_size);
// The bitmaps need to be cleared when free, but since this function is
// only used for shrinking the clear argument is correct but not crucial.
assert(size_in_bits <= _bitmap[0].size(), "Only used for shrinking");
_bitmap[0].resize(size_in_bits, true /* clear */);
_bitmap[1].resize(size_in_bits, true /* clear */);
}
void ZRememberedSet::delete_all() {
assert(is_initialized(), "precondition");
_bitmap[0].resize(0);
_bitmap[1].resize(0);
}
bool ZRememberedSet::is_cleared_current() const {
@ -77,15 +69,6 @@ bool ZRememberedSet::is_cleared_previous() const {
return previous()->is_empty();
}
void ZRememberedSet::clear_all() {
_bitmap[0].clear_large();
_bitmap[1].clear_large();
}
void ZRememberedSet::clear_current() {
current()->clear_large();
}
void ZRememberedSet::clear_previous() {
previous()->clear_large();
}

7
src/hotspot/share/gc/z/zRememberedSet.hpp
View File

@ -1,5 +1,5 @@
/*
* Copyright (c) 2021, 2023, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2021, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -114,8 +114,7 @@ public:
bool is_initialized() const;
void initialize(size_t page_size);
void resize(size_t page_size);
void delete_all();
bool at_current(uintptr_t offset) const;
bool at_previous(uintptr_t offset) const;
@ -133,8 +132,6 @@ public:
bool is_cleared_current() const;
bool is_cleared_previous() const;
void clear_all();
void clear_current();
void clear_previous();
void swap_remset_bitmaps();